Modulation of Cortical Activity Induced by High-Frequency Whole-body Vibration Exercise: An fNIRS Study.

CONTEXT: Whole-body vibration (WBV) has shown many positive effects on the human body in rehabilitation and clinical settings in which vibration has been used to elicit muscle contractions in spastic and paretic muscles.

OBJECTIVE: The purpose of this study was to investigate whether WBV exercise (WBVe) differently modulates the cortical activity associated with motor and prefrontal function based on its frequency.

METHODS: Eighteen healthy male adults (mean age: 25.3 ± 2.4 years) participated in this study and performed WBVe (Galileo Advanced plus, Novotec Medical, Pforzheim, Germany) under three different vibration frequency conditions (4-mm amplitude with 10-, 20- and 27-Hz frequencies) and a control condition (0 mm amplitude with 0-Hz frequency). Each condition consisted of two alternating tasks (squatting and standing) every 30 sec for five repetitions. All subjects performed the four conditions in a randomized order.

MAIN OUTCOME MEASURES: Cortical activation during WBVe was measured by relative changes in oxygenated hemoglobin (oxyHb) concentration over the primary motor cortex (M1), premotor cortex (PM), supplementary motor area (SMA), and prefrontal and somatosensory cortices using functional near-infrared spectroscopy (fNIRS).

RESULTS: OxyHb concentration was higher during the 27-Hz vibration condition than the control and 10-Hz vibration conditions. Specifically, these changes were pronounced in the bilateral M1s (p < 0.05) and right prefrontal cortex (p < 0.05). In contrast, no significant changes in oxyHb concentration were observed in any of the cortical areas during the 10-Hz vibration condition compared with control condition.

CONCLUSION: This study provides evidence that the motor network and prefrontal cortical areas of healthy adult males can be activated by 27-Hz WBVe. However, WBVe at lower frequencies did not induce significant changes in cortical activation.